The development of downhole instrumentation to evaluate drilling and coring of earth formations, has been given impetus by various governmental committees and councils. The Committee of Engineering Support for Deep Ocean Drilling for Science of the Marine Board of the National Research Council, e.g., joined with the Joint Oceanorgraphic Institutions Board (scientific advisors to National Science Foundation's ocean drilling programs) to sponsor a "Symposium on Measurement While Drilling". The proceeding of the meeting are found in "Technologies for Measurement While Drilling" National Academy Press, Washington DC, 1982. Prognosis: While instrumentation and uses involving measurements while drilling or (or "MWD"), are well-documented, gains to be obtained from measurements while coring (or "MWC"), have not yet crystallized.
Reasons: Many of most difficult well control problems occur when a core barrel is the well bore. Not only is the ability to handle well kicks reduced (because of reduced circulation capability) but there is increased likelihood of plugging and jamming. That is to say, the benefits to be gained from MWC during exploratory coring have not been documented in sufficient fashion to outweigh the safety concerns of the field operators. The above symposium had proposed use of a multisensor device to monitor coring operations, and the latter device included means for determining in real-time: weight-on-bit, torque-on-bit, resistivity, gamma response and core travel via acoustic response. Such a multisensor device is not only difficult to justify in view of the above, but it is also extremely expensive to manufacture.